1. Field of the Invention
The present invention relates to a suspension stacker crane, and particularly relates to a suspension stacker crane including a transferring device movably suspended from driving trucks.
2. Description of the Related Art
A conventional automated storage has a plurality of racks. The racks are arranged in parallel and each include a plurality of shelves arrayed in an extending direction and a vertical direction.
Further, the automated storage has a stacker crane as a transporting device for unloading an article onto the rack shelf or loading an article from the rack shelf. The stacker crane includes a travelling device that travels along a rail, a transferring device, and a lifting device that moves the transferring device in the vertical direction. Part of the rail is disposed laterally side by side with the rack. In a position lateral to the rack, the stacker crane moves the transferring device close to a target shelf, and transfers an article in that state (e.g., see Unexamined Japanese Patent Publication No. 2007-70086).
The travelling device in the stacker crane is made up of a variety of motors, travelling wheels, and the other devices, for example.
Given that some of articles to be transferred are heavy while some are light, it is considered that a stacker crane capable of transferring a heavy article is previously prepared, and that stacker crane transfers a light article as well as a heavy article. Alternatively, it is considered that a travelling device being a different type depending on the kind of article is provided in the stacker crane.
However, in the former case, a large-sized stacker crane is to be used at all times. In the latter case, a different travelling device is to be provided in each stacker crane. In either case, the cost may become high.